<s>
The	O
Electrologica	B-Device
X8	I-Device
(	O
or	O
EL	O
X8	O
)	O
was	O
a	O
digital	O
computer	O
designed	O
as	O
a	O
successor	O
to	O
the	O
Electrologica	B-Device
X1	I-Device
and	O
manufactured	O
in	O
the	O
Netherlands	O
by	O
Electrologica	O
NV	O
between	O
1964	O
and	O
1968	O
.	O
</s>
<s>
Like	O
its	O
predecessor	O
,	O
the	O
X1	B-Device
,	O
the	O
X8	O
system	O
included	O
core	B-General_Concept
memory	I-General_Concept
,	O
27-bit	O
word	O
length	O
,	O
and	O
drum	B-General_Concept
memory	I-General_Concept
as	O
secondary	O
storage	O
(	O
not	O
as	O
primary	O
storage	O
)	O
.	O
</s>
<s>
Unlike	O
the	O
X1	B-Device
,	O
the	O
arithmetic	O
unit	O
of	O
the	O
X8	O
included	O
floating	B-Algorithm
point	I-Algorithm
arithmetic	I-Algorithm
,	O
with	O
a	O
41-bit	O
mantissa	O
and	O
12-bit	O
exponent	O
(	O
which	O
adds	O
up	O
to	O
53	O
bits	O
rather	O
than	O
54	O
;	O
the	O
reason	O
is	O
that	O
there	O
are	O
two	O
copies	O
of	O
the	O
mantissa	O
sign	O
bit	O
)	O
.	O
</s>
<s>
The	O
system	O
is	O
most	O
notable	O
as	O
the	O
target	O
processor	O
for	O
Edsger	O
Dijkstra	O
's	O
implementation	O
of	O
the	O
THE	B-Operating_System
multiprogramming	I-Operating_System
system	I-Operating_System
.	O
</s>
<s>
This	O
includes	O
the	O
invention	O
of	O
semaphores	B-Operating_System
,	O
enabled	O
by	O
a	O
specific	O
instruction	O
in	O
the	O
X8	O
instruction	O
set	O
.	O
</s>
<s>
Semaphores	B-Operating_System
were	O
used	O
not	O
only	O
as	O
a	O
synchronization	O
mechanism	O
within	O
the	O
THE	B-Operating_System
operating	I-Operating_System
system	I-Operating_System
,	O
but	O
also	O
in	O
the	O
request	O
and	O
response	O
data	O
structures	O
for	O
I/O	O
requests	O
processed	O
by	O
the	O
CHARON	O
coprocessor	O
.	O
</s>
